This invention deals with a method for manufacturing complex metallic plates. At first the hollow metal piece, which will form the outer layer, is made. Then the metallic powder which will become the inner layer is filled in the metal piece. A multi-layer metallic plate can be manufactured by hot-rolling the above metal piece.
In the past, manufacturing complex metallic plates by first making the hollow metal piece for the outer layer and then pouring casting metal into the hollow part has been one of the typical methods of manufacturing complex metallic plates. However, this method is not suitable for mass production and has only been industrialized in special fields, such as the manufacture of rollers for rolling machines. For example, a well-known method is to make hollow metal pieces by casting metal for the outer layer into the mold and by draining unsolidified metal from the bottom of the mold after a certain thickness of solidified metal is molded. Then, the molten metal which will make the inner layer is poured inside of this molded metal.
The present method is also a good example from the point of view of obtaining excellent adhesive surfaces between layers of metals. In order to obtain the excellent adhesive surfaces by preventing air oxidation of the inside of the hollow metal piece when the molten metal for the outer layer is poured, flux with low oxygen or organic resin is applied to the inner surfaces of the hollow metal beforehand. This method is considerably effective in preventing air oxidation and in preventing the agglutination of the oxide particles which will be formed during the injection of the molten metal to surfaces.
However, these prior art methods all require the pouring of the molten metal inside the hollow metal piece. In the process of solidification of the molten metal which will become the inner layer, problems such as considerable segregation occur in many cases. Further, any interpositions would adhere to the surfaces and cause poor adhesion. That would result in a metallic plate of poor mechanical quality.